Gravity from Local Lorentz Violation

TL;DR

This paper explores a novel theory of gravity where masslessness of gravitons results from spontaneous local Lorentz violation, matching general relativity at low energies but offering new experimental and theoretical insights.

Contribution

It introduces a gravity model based on spontaneous local Lorentz violation, providing an alternative explanation for graviton masslessness beyond diffeomorphism symmetry.

Findings

Reproduces Einstein-Hilbert action at low energies

Predicts detectable signals in sensitive experiments

Implications for fundamental understanding of gravity

Abstract

In general relativity, gravitational waves propagate at the speed of light, and so gravitons are massless. The masslessness can be traced to symmetry under diffeomorphisms. However, another elegant possibility exists: masslessness can instead arise from spontaneous violation of local Lorentz invariance. We construct the corresponding theory of gravity. It reproduces the Einstein-Hilbert action of general relativity at low energies and temperatures. Detectable signals occur for sensitive experiments, and potentially profound implications emerge for our theoretical understanding of gravity.